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arXiv · 1211.7171

Gradient echo memory in an ultra-high optical depth cold atomic ensemble

B. M. Sparkes·J. Bernu·M. Hosseini·J. Geng·Q. Glorieux·P. A. Altin·P. K. Lam·N. P. Robins·B. C. Buchler
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Abstract

Quantum memories are an integral component of quantum repeaters - devices that will allow the extension of quantum key distribution to communication ranges beyond that permissible by passive transmission. A quantum memory for this application needs to be highly efficient and have coherence times approaching a millisecond. Here we report on work towards this goal, with the development of a $^{87}$Rb magneto-optical trap with a peak optical depth of 1000 for the D2 $F=2 \rightarrow F'=3$ transition using spatial and temporal dark spots. With this purpose-built cold atomic ensemble to implement the gradient echo memory (GEM) scheme. Our data shows a memory efficiency of $80\pm 2$% and coherence times up to 195 $\mu$s, which is a factor of four greater than previous GEM experiments implemented in warm vapour cells.

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B. M. Sparkes, J. Bernu, M. Hosseini, J. Geng, Q. Glorieux, P. A. Altin, P. K. Lam, N. P. Robins, B. C. Buchler. 2012-11-30. Gradient echo memory in an ultra-high optical depth cold atomic ensemble. https://doi.org/10.1088/1367-2630%2F15%2F8%2F085027

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